spe 130376 slides
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Economics of constructing deep HPHT gas wells with formate brinesTRANSCRIPT
SPE 130376
A Review of the Impact of the Use of Formate Brines on the Economics of Deep
Gas Field Development Projects
John Downs
Cabot Specialty Fluids
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Deep gas wells are expensive .....
•12 times more expensive than conventional gas wells *
•Last 10% of deep gas well accounts for 50% of total well cost *
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
* US Department of Energy website - Onshore gas well costs in USA** Snead (2005) - The Economics of Deep Drilling in Oklahoma
Gas well cost versus depth**
Some basic principles for improving the economics of deep gas field developments ?
Working at depth is expensive, so.. :
•Use technologies that will accelerate deep well construction *
• Get it right first time – avoid costly interventions
• Know what is down there - ensure accurate reservoir evaluation
•Focus on recovering your substantial investment - extract
recoverable reserves as fast as the reservoir (engineers) will allow
* US DOE ”Deep Trek” R&D programme aimed at identifying some of these technologies
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
How can well construction fluids influence economics of deep gas field developments ?
WCF performance impacts on costs and revenues
• Time taken to drill and complete the required wells • Well design and placement • Well control and safety • Well integrity, lifetime and maintenance • Logging capability and interpretation • Waste management and liabilities • Rate of recovery of reserves
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Extreme conditions in deep wells expose the performance
deficiencies of conventional WCF
High temperatures and hydrothermal chemistry -Barite sag, leading to well control problems -Need gels, causing high swab, surge and start-up pressures-Corrosive gas influx into halide brines will destroy ”corrosion resistant alloys”
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Super 13Cr, 1 month 22Cr, 2 months 25Cr, 2 months
Extreme conditions in deep wells expose the performance
deficiencies of conventional WCF
High pressures and hard rocksHigh solids loading have negative effects on ECD, ROP, bit life, swab and
surge, differential sticking, hole cleaning, tools, screens, seals, formation, etc ......!
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Effect of Mud on Rate of PenetrationCarthage Marble with 7 Blade PDC Bit
0
10
20
30
40
50
0 5,000 10,000 15,000 20,000 25,000 30,000
Weight on Bit (lbf)
Ra
te o
f P
en
etr
ati
on
(ft
/hr)
Water
16ppg OBM
16ppg CsFm
16ppg OBM + Mn
From :SPE 112731 “Optimisation of Deep Drilling Performance with Improvements in Drill Bit and Drilling Fluid Design”
Best fluid for high ROP and long bit-life is solids-free water …
Extreme conditions in deep gas wells expose the
performance deficiencies of conventional WCF
Narrow drilling windows, aggravated by pressure depletion from
production
-Production while drilling lowers pore pressure and fracture gradient -Solids-weighted muds may not be able to stay within ECD limits-Well control problems if fracture pressure gradient exceeded -Increasingly the domain of MPD and ”designer fluids” providing Fracture Gradient
Enhancement (FGE) or Stress Caging effects
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
FGE - Increasing hoop stresses around the well bore by creating short stabilised fractures
Conventional high-density completion fluids used in deep
gas wells have a high cost of ownership
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Software tool now available that calculates the full cost of
owning and using high-density completion fluids
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Prices the full operational costs, waste costs and the cost of “incidents”
Cost of fluid ownership
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
- Purchase /leasing fee - Transport onshore /offshore- Sub-optimal rig time- Well clean up time - Waste treatment and disposal - Stand-by time - Isolation and treatment of produced water - Production delays - Production handover delays - Liabilities and legal fees
arising from splashes, spills, releases
Factors in damage caused to company reputation by incidents
BrineWise tool calculates all fluid ownership costs
So.. do conventional WCF influence the economics of deep gas field developments ?
Undoubtedly YES – conventional WCF have problems and influence economics by increasing overall development costs of deep gas fields
• Lengthening the time taken to drill and complete • Creating well control and safety risks • Degrading well integrity/durability • Raising waste management costs and liabilities – i.e. high cost
of
ownership
...And if they are damaging to the formation they may
reduce the rate of revenue generation
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
How do you make a WCF that performs better under
extreme conditions in deep gas wells ?
Remove the source of the problems -Remove the solid-weighting agents -Remove any halide salts (chlorides and bromides) -Preferably remove any hydrocarbons too (well control risk and logging issues)
Formate brines developed by Shell Research, 1985-95
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Density to SG 2.3 /19.2 ppg/143 pcf
No solids No halides No hydrocarbons Anti-oxidant
Drilling, completion, workover and suspension fluids for deep gas wells
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
W-Cluster
15000'
Z2
Z6
Z5Z7
Z4
5000'
10000'
15000'
18000'
1995 – Formate brines used for first time by Mobil to drill and work over deep gas wells, onshore, northern Germany
Walsrode field – onshore, high-angle slim hole wells Z1, Z5, Z6 and Z7
TVD : 4,450-5,547 metres Reservoir: Sandstone 0.1-125 mDBHST : 315oF (157o C) Section length: 345-650 metres
Outcome of Mobil’s first drilling trials with formate brines in
onshore deep gas wells - 1995/96
Absence of weighting solids has a clear impact on efficiency and
economics 1,2
“Use of formate drilling fluid ….eliminated most of the previous hole problems
...resulted in a dramatic increase in drilling performance and hydraulics…
and significantly reduced well costs”
Low-solids drilling fluid concept appears to be validated
1) Sundermann, R. and Bungert, D.: “Potassium-Formate-Based Fluid Solves High Temperature Drill-In
Problem,” Journal of Petroleum Technology (November 1996) 1042
2) Bungert, D., Maikranz, S., Sundermann, R., Downs, J., Benton, W. and Dick, M.A.: “The Evolution and
Application of Formate Brines in High-Temperature/High-Pressure Operations”, IADC/SPE 59191, IADC/SPE
Drilling Conference, New Orleans, 23-25 February 2000.
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Formate brines used by Mobil in 15 deep gas well
constructions in northern Germany 1995-1999 (SPE
59191)
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Well Name Application Fluid Type Density s.g. (ppg)Horizontal Length(m)
Angle (°) BHST (°F) BHCT (°F) TVD (metres) MD (metres) Permeability (mD)
Walsrode Z5 W/C K Formate 1.55 (12.93) 345 26 315 na 4450 - 4632 4815 - 5151 0.1 - 125 mD
Wasrode Z6 W/C K Formate 1.55 (12.93) 420 40 315 na 4450 - 4632 4815 - 5151 0.1 - 125 mD
Walsrode Z7 Drill-In K Formate 1.53 (12.77) 690 59 315 295 4541 - 4777 5136 - 5547 0.1 - 125 mD
Söhlingen Z3A Drill-In Formix 1.38 (11.52) 855 89 300 270 4908 5600 na
Söhlingen Z3a Drill-In Na Formate 1.30 (10.85) 855 89 300 270 4908 5600 na
Volkersen Z3 W/C Formix 1.40 (11.68) 512 52 320 na na na na
Kalle S108 Drill-In Formix 1.45 (12.10) 431 60 220 na 6000-6500 6200-6600 na
Weißenmoor Z1 W/C Formix 1.35 (11.27) 634 31 300 na na na na
Idsingen Z1a Drill-In K Formate 1.55 (12.93) 645 61 321 290 4632 - 4800 5257 - 5821 0.1 - 125 mD
Söhlingen Z12 Drill-In Na Formate/Formix 1.35 (11.27) 452 28 313 285 4736 - 4937 4846 - 5166 1.0 - 75 mD
Simonswolde Z1 Drill-In K Formate/Formix 1.52 (12.68) 567 35 293 275 4267 - 4572 4236 - 4648 0.1 - 25 mD
Walsrode NZ1 Drill-In Formix 1.51 (12.60) 460 34 290 265 4632 - 4815 4541 - 4693 0.1 - 125 mD
Idzingen Z2 W/C Formix 1.40 (11.68) na na 320 na 4632 - 4800 5257 - 5821 0.1 - 125 mD
Voelkersen NZ2 W/C Formix 1.40 (11.680 na na 320 na na na na
Söhlingen Z13 Drill-In/Frac K Formate/Formix 1.30 (-1.56)(10.85) 1200 90 300 285 4724 5486 - 6400 0,1 - 150 mD
Huldra field, HP/HT gas condensate -BHST: 297oF-TVD : 3,900 metres/12,795 ft - Fluid density: 15.75 ppg/118 pcf - 6 wells – 600 ft reservoir sections 5-7/8” at 45-55o
- 1–2,000 mD sandstone-Open hole, wire wrapped screens
Justification for using formate - Improve well control ! - Lower ECD- Run completion in same fluid - Low risk of screen plugging - Shale stabilisation - Lubricating- Safe for crews - Environmentally benign
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
2001 - Formate brines used for first time by Statoil to drill and complete 6 deep HPHT gas wells, offshore, Norway
Operator had experienced kicks when using barite-weighted fluids
Outcome of Statoil’s first drilling trials with formate brines in
offshore deep gas wells - 2001/02
Efficiencies and economies provided by drilling at depth with low-
solids brine 1
“Stable hole, low ECD, good hole cleaning and stable fluid has led to rig time savings due to:
•Fast tripping speed•Fast casing running speeds•Less mud conditioning and wiper trips than with conventional drilling fluids”
Low-solids fluid enables faster well constructions at depth
1) Saasen, A., Jordal, O.H., Burkhead, D., Berg, P.C., Løklingholm, G., Pedersen, E.S., Turner, J. and Harris, M.J.:
“Drilling HT/HP Wells Using a Cesium Formate Based Drilling Fluid,” IADC/SPE 74541, IADC/SPE Drilling
Conference, Dallas, 26-28 February 2002.
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Deep and/or HPHT gas fields developed using formate
brines as WCF 1995-2009
Author has good information on 35 fields
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Some deep and/or HPHT gas fields developed using formate brines
Country Fields Reservoir Description
Matrix
type
Depth, TVD
(metres)
Permeability
(mD)
Temperature
(oC)
Germany Walsrode,Sohlingen
Voelkersen,Idsingen
Sandstone 4,450-6,500 0.1-150 150-165
Hungary Mako Sandstone 5,692 - 235
Kazakhstan Kashagan Carbonate 4,595-5,088 - 100
Norway Huldra ,Njord
Kristin,Kvitebjoern
Tune, Valemon
Victoria
Sandstone 4,090-7,380 50-1,000 121-200
Pakistan Miano, Sawan Sandstone 3,400 10-5,000 175
Saudi Arabia Andar,Shedgum
Uthmaniyah
Hawiyah,Haradh
Tinat, Midrikah
Sandstone
and
carbonate
3,963-4,572 0.1-40 132-154
UK Braemar,Devenick
Dunbar,Elgin
Franklin,Glenelg
Judy, Jura, Kessog
Rhum, Shearwater
West Franklin
Sandstone 4,500-7,353 0.01-1,000 123-207
USA High Island Sandstone 4,833 - 177
Formate brine used in > 140* deep and/or HPHT gas wells , 1995- present
Drilling, completion, workover, suspension and packer fluids
•At densities up to SG 2.25 (18.7 ppg or 140.2 pcf)
•At BHST up to 235oC (450oF)
• For periods of > 10 years dowhole (packer fluid applications)
•In sandstone and carbonate reservoirs, 0.01 mD up to 4 Darcy
•Wide variety of completions – barefoot open hole, cased and
perforated, with sand screens and gravel packs
* Actual field/well numbers will be greater – but some are not documented
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Deep gas fields where formate brines have been used as WCF – segmented by operator
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Aramco 7
Total 8
Statoil 6
ExxonMobil
4
BP 3
Oth-ers 7
Formate brines used in the world’s largest HPHT gas field development – Elgin/Franklin
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Also the deepest HPHT gas field in North Sea
B
190oC1100bar
5300m
Water Depth 90m
SIWHPFWHT
830bar180oC
::
GASCONDENSATE
3-4% C0230-40 ppm H2S
320barDEWPOINT
30% O1 Darcy K
Cesium formate brine used by TOTAL in 34 well construction operations in 8 deep gas fields in period 1999-2009
Gaining an economic perspective – Scope of review
•Only examined Cs formate brine applications (more extreme conditions)
•128 user observations extracted from 5 published field case histories
•8-year production figures found for two HPHT gas fields drilled and
completed entirely with potassium/cesium formate brines
•Observations on well construction efficiencies tend to be qualitative
rather than quantitative
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
1) Collect and analyse user observations on operational well construction efficiencies
2) Look for examples of long-term production rates, for evidence of production efficiencies
Economic benefits from use of formate brines in deep gas
field developments – Results of review
“ a remarkable record of zero well control incidents in all 15
HPHT drilling operations and 20 HPHT completion operations”
Operational efficiencies provide well construction cost reductions
1. Better drilling environment gives rig-time savings - Stable hole: see LWD vs. WL calipers in shale
- Elimination of well control and stuck pipe incidents - Good hydraulics, low ECD
- Good ROP in hard abrasive rocks
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Economic benefits from use of formate brines in deep gas
field developments – Results of review
Operational efficiencies provide well construction cost reductions
2. Allowing faster and easier movements of tubulars and fluids - Pipe and casing running speeds are faster
- Mud conditioning and flow-check times shorter - Displacements simplified, and sometimes eliminated (i.e. formate drilling fluid = formate completion fluid)
Quote by operator : “ Improved well economics by increasing trip speed”
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Economic benefits from use of formate brines in deep gas
field developments – Results of review
Operational efficiencies provide well construction cost reductions
3. Faster completions
HPHT gas well completion timesfrom the Rushmore database
- Wells drilled with OBM vs cesium formate brine
Quote by operator : “ fastest HPHT completion operation ever performed in North Sea (12.7 days)”
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Efficient delivery of gas reserves (revenues)
Tune and Huldra fields – drilled and completed with formate brines
90% recovery of reserves (16-18 billion m3) produced in 7 to 8 years
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
0 2 4 6 8 10 120
10
20
30
40
50
60
70
80
90
100
HuldraTune
Time since start-up (years)
Re
co
ve
ry o
f G
as
Re
se
rve
s (
%)
Source : Norwegian Petroleum Directorate- Fact Pages - November 2009
Efficient delivery of condensate reserves (revenues)
Tune and Huldra fields – drilled and completed with formate brines
90% recovery of reserves (3-5 million m3) produced in 4 to 6 years
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Source : Norwegian Petroleum Directorate- Fact Pages - November 2009
0 1 2 3 4 5 6 7 8 9 100
20
40
60
80
100
120
HuldraTune
Time since start-up (years)
Re
co
ve
ry o
f C
on
de
ns
ate
Re
se
rve
s
(%)
Conclusion
Results of this review suggests that the use of formate brines in deep gas field developments has reduced well construction times and costs by :
- Providing a better drilling environment - Allowing faster/easier movements of WCF and hardware - Allowing faster completions
The non-damaging nature of formate brines may have contributed to the efficient production of recoverable hydrocarbon reserves from two HPHT gas/condensate fields examined in this study.
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Footnote 1
Results of independent Eco-efficiency study by BASF show thatcesium formate brine is the most sustainable high-density completion fluid
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
Leasing of cesium formate brine encourages a sustainable approach
Footnote 2
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
“Using photoelectric factor and bulk density data, combined with resistivity measurements from both the LWD drill pass and the ream pass, produces a very reliable and consistent net reservoir definition.”
Good reservoir definition in cesium formate brine
Footnote 3
2010 SPE Deep Gas Conference, Bahrain, 24-26 January
“Applying a conductive drilling fluid in all production wells drilled in a field also provides the possibility of running high quality resistivity image logs (FMI). Extensive use of such logs provides the geo-modelers with detailed information regarding structural dip, depositional environment, sedimentary features, facies, and geological correlations.”
Good reservoir definition in cesium formate brine